The class of polymers of carbon monoxide and olefin(s) has been known for some time. Brubaker, U.S. Pat. No. 2,495,286, produced such polymers of relatively low carbon monoxide content in the presence of free radical initiators, e.g., peroxy compounds. U.K. Pat. No. 1,081,304 discloses related polymers of higher carbon monoxide content produced in the presence of trialkylphosphine complexes of palladium salts as catalyst. Nozaki extended the reaction to produce linear alternating polymers in the presence of triarylphosphine complexes of palladium moieties and certain inert solvents. See, for example, U.S. Pat. No. 3,694,412.
More recently, the class of linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon has become of greater interest in part because of the greater availability of the polymers. The more recent processes for the production of the linear alternating polymers, now becoming known as polyketone polymers or polyketones, are illustrated by number of published European Patent Applications including 121,965, 181,014, 213,671 and 257,663. The process generally involves the use of a catalyst composition formed from a compound of a Group VIII metal selected from palladium, cobalt or nickel, the anion of a non-hydrohalogenic acid having a pKa below 2 and a bidentate ligand of phosphorus, arsenic or antimony.
The resulting polymers are relatively high molecular weight thermoplastic materials having utility in the production of shaped articles such as containers for food and drink and as parts and housings for the automotive industry, which articles are produced by methods conventional for thermoplastics such as extrusion, injection molding or thermoforming. These polymers are now considered to be conventional.
Although the polyketone polymers are relatively stable and have good properties, the linear alternating polymers do undergo to some extent the thermal degradation that is characteristic of most if not all organic polymers. There are a large number of thermal stabilizers which are employed commercially to stabilize thermoplastic polymers against such degradation. However, many of the thermal stabilizers which are known to be effective with polyolefins, polyamides or polyacrylates are not effective when employed with linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon. Russell et al, U.S. Pat. No. 3,929,729 and U.S. Pat. No. 4,024,104, teach the use of certain benzophenones and certain benzotriazines, respectively, as thermal stabilizers for a broad range of polymers of carbon monoxide and ethylene with the optional presence of third monomers. The scope of the polymers disclosed by Russell et al is relatively broad but the polymers tested ar relatively limited and the Russell et al disclosure does not appear to be specifically directed toward linear alternating polymers. It would be of advantage to provide for the efficient stabilization of such linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon against thermal degradation.